Disease symptoms are sometimes the result of your immune system doing its job. Ever
wondered why fever comes before or during a flu attack? Its presence usually signifies the
response of your body's immune system to the threat, which could be bacteria or viruses.

In the case of a common cold, the immune system responds to the rhinovirus invading the
epithelial cells in your upper chest by sending white blood cells to the area, which opens up
blood vessels through inflammation and increases mucus secretions causing your nose to be
stuffed and runny.